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www.univ-amu.fr www.lam.fr PhD Thesis PhD thesis director name: Stéphane BASA Email: sté[email protected] Phone number: +6 37 21 61 20 Co-director: Sandra SAVAGLIO (Physics Department, University of Calabria, Italy) PhD title: Exploring the dawn of the Universe with the Sino-French SVOM mission Subject description (1 page max.): Gamma Ray Bursts (GRBs), the most powerful explosions since the formation of our Universe, are unique cosmic events. Lasting from a few milliseconds to several minutes, the radiation emitted in this interval is equivalent to that of the Sun over its entire life. They are hundreds of times brighter than a typical supernova, the ultimate end of a massive star. Due to the extreme luminosity of their multi-wavelength emissions, they are now considered as one of the best ways to probe the dawn of the Universe. The tremendous luminosity of both the prompt gamma-ray emission, and the X-ray and optical afterglow indicates that GRBs should be visible out to large distances, when the universe was only a few hundreds million years old (redshift z > 10). France and China just agreed to co-build the SVOM mission, dedicated to the detection and observation of GRBs (launch date: 2021). This mission is the proud successor (and, the moment, the only one approved) to the SWIFT mission, and will provide a systematic study of all types of bursts (e.g., short or distant). It has been carefully designed to allow a very high scientific return, thanks in particular to the organization of an ambitious multi-wavelength follow-up. The latter is based on a complex system involving a network of 1-m telescopes, which automatically and quickly follow the alerts, and larger diameter telescopes (e.g., VLT, ALMA, E-ELT, JWST) for very deep observations. The student will actively work on the implementation of the system, in particular by optimizing the search for the most distant bursts (beyond z = 5). He/she will have to develop the system allowing the identification of the farthest GRBs with the network of 1-m robotic telescopes and to implement a system allowing an efficient triggering of the largest telescopes. He/she will work in close collaboration with CPPM, IRAP and CEA in France, NAOC in China, University of Calabria in Italy, etc. Moreover, to have a deep knowledge of the scientific needs, student will also conduct studies on the galaxies hosting the GRB. Indeed GRBs offer a unique opportunity to localize galaxies independently of their optical/NIR luminosities, and, thus, single out a population, which is hard to detect with traditional means. This approach has shown in the past large consequences on our understanding of galaxy formation and evolution. The student will work on multi-wavelength observations, from radio to optical domains from the latest far-infrared, submillimeter and radio telescopes (e.g., SCUBA-2, ALMA). The estimated Spectral Energy Distribution (SED) of the sample of hundreds of GRB host galaxies will be compared to synthetic models to derive, for each galaxy, key environmental features, such as star-formation history, stellar age, metal content, stellar mass, dust mass and temperature. It will be then possible to investigate how the UV/optical and radio derived SFRs can be reconciled. The student will have to actively participate to the preparation of observational proposals, and lead observations, data processing and final scientific analysis. He/she will lead some of the publications associated with these observations and other data publicly available. He/she will then play a key role during all necessary steps, making him/her a professional astronomer. He/she will work with two experienced teams, LAM in Marseille (France) and University of Calabria (Italy). The student will have to spend a fraction of his/her time in Italy. This Ph'D is proposed in the framework of the SVOM mission and of the European Research Network, GDRE, Exploring the Dawn of the Universe with Gamma-Ray Bursts. Références bibliographiques: • L. Hunt et al. New light on gamma−ray burst host galaxies with Herschel, Astronomy & Astrophysics, Volume 565, id.A112, 2014 • M. Michalowski et al. Spatially−resolved dust properties of the GRB 980425 host galaxy, Astronomy & Astrophysics, Volume 562, id.A70, 2014 • P. Schady et al., Herschel observations of gamma-ray burst host galaxies: implications for the topology of the dusty interstellar medium, MNRAS, 2014 • S. Basa et al., Constraining the nature of the most distant Gamma-Ray Burst host galaxies, A&A 2012 • S. Savaglio et al., The Galaxy Population Hosting Gamma-Ray Bursts, ApJ, 2009